In recent years, higher bit color depth rather than the conventional eight bit color depth is more and more desirable in many fields, such as scientific imaging, digital cinema, high-quality-video-enabled computer games, and professional studio and home theatre related applications. Accordingly, the state-of-the-art video coding standard—H.264/AVC—has already included Fidelity Range Extensions, which support up to 14 bits per sample and up to 4:4:4 chroma sampling.
However, none of the existing high bit coding solutions supports color bit depth scalability. Assume that we have a scenario with 2 different decoders (or clients with different requests for the color bit depth, e.g. 12 bit) for the same raw video. The existing H.264/AVC solution is to encoder the 12-bit raw video to generate bitstream no. 1 and then convert the 12-bit raw video to an 8-bit raw video and encode the 8-bit counterpart to generate bitstream no. 2. If we want to deliver the video to different clients that request different bit depths, we have to deliver it twice, or put the 2 bitstreams in one disk together. It is of low efficiency regarding both the compression ratio and the operational complexity.